Preheat your oven to 375°F (190°C) and grease a 9x12-inch casserole dish.

In a large skillet, heat olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until translucent.

Add minced garlic, chili powder, and ground cumin, and cook for an additional minute.

Stir in the cooked shredded chicken and cook for 2-3 minutes.

In a separate bowl, whisk together the salsa verde and sour cream until smooth.

Spread one-third of the salsa verde mixture on the bottom of the greased dish. Layer half of the corn tortillas, followed by half of the chicken mixture, and a cup of cheese. Repeat layers.

Bake for 15-20 minutes until the cheese is melted and bubbly.

Let cool for 5-10 minutes before serving, topping with cilantro and any optional toppings.